1. Field of the Invention
This invention relates generally to digital data transmission, and more particularly to a method for such transmission as a serial stream of N-bit words, each word being transmitted in a parallel format of the bits arranged with frequency spacing within a standard FCC channel.
2. Description of Related Art
Communication by wireless transmission with both analog and digital signals is well known in the art. Analog signals vary with time, frequency, amplitude or other characteristics of the signals in order to impress information onto the signals. Generally speaking digital signals vary simply by being in one of two or more signal states at each moment in time. Paging is an important application that has moved to standardize on the use of digital data transfer and is most often uses a binary coding system. Typical assigned bandwidth are in the range of 25 KHz. And state of the art technique is to use serial transmission either in two or four level code. Within an assigned bandwidth of 25 KHz typically 10 KHz is used to transmit binary data and the remaining 15 KHz is used as guard bands to insure separation of one channel to the next. A given signal is typically transmitted by tuning the transmitter to a frequency that is 5 KHz above and a second frequency that is 5 KHz below the center of the band in order to represent binary ones and zeros respectively. Currently, the state of the art is limited to approximately 6400 bits of information per second due to inherent physical limitations in the propagation of electromagnetic energy signals.
To improve on the rate of data transmission it will be necessary to either transmit at a higher rate of speed, improve the pulse rate per second, or pack additional pulses in parallel into the existing bandwidth. The latter technique is the subject of the present invention.
The prior art teaches the use of narrow band transmission of digital data signals. However, the prior art does not teach that such signals may consist of parallel bursts of binary formatted data. The present invention fulfills these needs and provides further related advantages as described in the following summary.